Fluctuation of intraocular pressure in Chinese patients with pigment dispersion syndrome after drug-induced mydriasis

This study investigates the characteristics of intraocular pressure (IOP) fluctuations in Chinese patients with pigment dispersion syndrome (PDS) after drug-induced mydriasis. In this prospective cohort study, 26 PDS patients were identified and instilled with 0.5% tropicamide and phenylephrine twice randomly in one of the 2 eyes, after which IOP and pupil diameter (PD) were measured hourly for 8 hours. A slit-lamp examination was performed after each measurement. Post-mydriatic IOPs and PDs were compared with baseline. The average IOP increased to a maximum of 18.3 ± 4.9 mm Hg (vs 16.7 ± 4.5 mm Hg at baseline; P = .002) 1 hour after dilation. Accordingly, the PD reached its peak (8.3 ± 0.6 mm vs 5.9 ± 1.0 mm; P < .001). By the end of the 8-hour observation period, mean IOP had decreased to 17.4 mm Hg and mean PD to 7.1 mm. The majority of these eyes (88.5%, 23/26) exhibited mild IOP elevation of 2.5 ± 1.4 mm Hg (range: 0–4.9 mm Hg). In the non-laser peripheral iridotomy group, 2 eyes (13.3%, 2/15) developing moderate anterior chamber pigment shedding showed an increase in IOP of ≥ 5 mm Hg after dilation (21.1 and 12.6 mm Hg); 1 eye (9.1%, 1/11) receiving laser peripheral iridotomy showed a similar IOP increase (5.1 mm Hg). All clinically significant IOP elevations were resolved without treatment. No post-mydriatic IOP ≥ 40 mm Hg was detected during the study. Drug-induced mydriasis appears relatively safe in the majority of Chinese PDS patients, with generally mild effect in most. However, caution remains warranted in eyes with prominent anterior chamber pigment shedding.